This invention relates generally to surgical devices for stabilizing the spine, and more particularly to a spinal implant for use in fusing and stabilizing adjoining spinal vertebrae.
Chronic back problems cause pain and disability for a large segment of the population. In many cases, the chronic back problems are attributed to relative movement between vertebrae in the spine. Spinal surgery includes procedures to stabilize adjacent vertebrae. Common stabilization techniques include fusing the vertebrae together.
Fusion techniques include removing disc material which separates the vertebrae and impacting bone into the disc area. The impacted bone fuses with the bone material of the vertebrae to thereby fuse the two vertebrae together. In a further advance in the art, spinal implants have been developed to increase the probability of a successful fusion. An example of such a spinal implant is shown in U.S. Pat. No. 5,489,308, which shows a threaded spinal implant which includes a hollow cylinder into which bone chips or bone slurry may be placed. The cylinder has holes extending radially therethrough. The bone material grows through the holes to fuse with the bone material of the vertebrae. Similar threaded spinal implants are disclosed in U.S. Pat. Nos. 5,489,307; 5,263,953; 5,458,638; and 5,026,373; the disclosures of all of the foregoing patents are incorporated herein by reference.
The metallic surfaces of these spinal implants, other than the threaded structure with large pores, is essentially smooth without pillars, micropillars or surface texturing. Without such surface texturing the spinal implants in some circumstances may not mechanically anchor at an early date or affix into the adjoining bone as much as is desirable, and may not effectively minimize fibrous capsule formation around the implant. There is a need for a spinal implant with pillars, micropillars, fins or surface texturing which addresses these problems and provides improvements in these areas; the present invention is such an implant.
A spinal implant comprising a hollow, generally tubular shell having an exterior surface, a first end and a second end. A plurality of pillars project from the exterior surface of the shell in a regular, non-helical array. Each pillar has a height of 100-4500 microns and a dimension in a direction perpendicular to the height of 100-4500 microns. The exterior surface has a plurality of holes therethrough to permit bone growth therethrough.